Method of and apparatus for vacuum drying of flat material in foil shape, especiallyleather



7 Feb 196 R. HOHMANN 3,303,574

METHOD OF AND APPARATUS FOR VACUUM DRYING OF FLAT MATERIAL IN FOIL SHAPE, ESPECIALLY LEATHER Filed April 5, 1965 2 Sheets-Sheet 1 it 3- o eb 14, 1967 R'HOHMANN 03,574

METHOD OF AND APPARATUS FOR VACUUM DRYING OF FLAT MATERIAL IN FOIL SHAPE, ESPECIALLY LEATHER Filed April 5, 1965 2 Sheets-Sheet 2 Patented Feb. 14, 1967 6 Claims. bi. 3416) The present i; *Iention relates to a method of and apparatus for vacuum drying flat material in foil shape, especially leather. It has been known heretofore to vacuum dry leather and similar flat foil-shaped material, by placing the wet leather upon a plate heated by hot water or steam, and smoothing out the thus placed leather by means of a slicker which smoothes out any folds or creases in the leather. Subsequently, -a cover of the apparatus which comprises means for pressing the leather against the heating plate is lowered onto the leather on the heating plate, and finally the leather is subjected to vacuum drying.

A method of this type has the drawback that the leather parts which are in contact with the heating plate will during the smoothening operation be subjected to. a rather high temperature which almost equals the temperature of the heating plate. Such strong heating of the leather, howev-er, harmfully affects the quality of the goods.

It is, therefore, an object of the present invention to provide a method of and apparatus for vacuum drying flat foil-shaped goods, especially leather, which will overcome the mentioned drawbacks.

It is another object of this invention to provide a method and apparatus of the above mentioned type which will not only improve the quality of the goods being treated but will also greatly improve the economy of the respective treatment of such goods.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 is a side view of an apparatus according to the present invention.

FIG. 2 shows to a top view of the arrangement shown in FIG. 1.

FIG. 3 illustrates on a larger scale than FIGS. 1 and 2 a section along the line III1II of FIG. 2.

The present invention is characterized primarily in that the fiat material, for instance leather, is placed in wet condition upon a cold drying plate supported by a working table and is smoothened out on said cold plate. Thereupon, the thus smoothened-out leather is introduced into a vacuum container where it is heated and vacuum dried. Simultaneously with the introduction of the smoothed-out leather on the cold drying plat-e into the vacuum chamber, another drying plate is moved from the vacuum chamber into a loading station, i.e. above the working table, where the dried leather is removed and the plate is charged with a new wet leather piece. The loading station is provided with a blower for cooling the heating plate which has just been moved from the drying chamber to the loading and unloading station so that the plate before being loaded with new material will be fairly cool.

Referring now to the drawing in detail, the apparatus according to the present invention comprises primarily a loading and unloading station generally designated I and a drying station generally designated II. The loading and unloading station I includes a working table 1 supported by a frame structure 2, while the drying station comprises a housing 3 (FIG. 3) encasing vacuum drying means. The arrangement according to the present invention furthermore comprises two drying plates 9 and 9a each of which is adapted alternately to be moved into the drying station and to the [loading station. To this end, the drying plates are adapted removably to be inserted into frames 6, 7 respectively connected to the upper and lower sections 5a and 5b of a pair of endless chains 4 and 5 respectively supported by sprockets wheels 4a, 4b and 5c and 5d. As will be seen from FIG. 2, the chains 4 and 5 extend alongside the frames 6 and 7 respectively supporting plates 9 and 9a. Each of said frames 6, 7 is provided with rollers 8. The rollers 8 of the upper frame 6 are adapted to roll on rails 8a (see FIG. 3) arranged alongside the path of upper frame 6, while the rollers of lower frame 7 are adapted to roll on rails 8b arranged alongside the path of the lower frame 7. As will be seen from the drawings, the paths of movement of the two frames 6 and 7 are at different levels so that the frames can, as stated above, alternately be moved from the loading station into the drying station, and vice versa, without interfering with each other. The arrangement is such that when one plate has reached its proper position in the drying station, the other plate has reached its proper loading position. The movement of the chains is preferably etfected by a controllable motor M (FIG. 1).

In conformity with the present invention, the plates 9, 9a are relatively thin, for instance they may have a thickness of 0.06 inch and a surface-s area of 126 inch times 71 inch. In order to be able sufliciently to support the drying plates during the placing of the leather thereon in the loading station, the working table is preferably equipped with raising and lowering means, for instance in the form of compressed air operable cylinder piston systems 10 for raising and lowering the working table.

For purposes of quickly cooling the respective drying plate moved out of the drying station to the loading station for unloading the dried material and loading the wet material, it is advantageous to design the working table 1 in the form of a grate and to provide a blower B below said grate for supplying cooling air.

The drying station has that portion of rails 81:, 8b which is located therein supported by supporting members 13 (FIG. 3) which in their turn are supported by springs 13a. The lower ends of springs 13a rests on stationary supports S. The lower ends of springs 13a are guided in tubular members T. The drying station furthermore includes a cover 11 connected to fluid operable piston means 12 reciprocable in cylinders 12a. These cylinders are in customary manner supplied with fluid inlets and outlets adapted to be connected to the pressure and suction sides of a pressure fluid source and are controllable for selectively lifting and lowering cover 11. For purposes of uniform lifting and lowering action upon cover 11, the inlets to said cylinders 12a may be interconnected, and correspondingly also the outlets of said cylinders 12a may be interconnected.

Cover 11 (FIG. 3) is in a manner known per se equipped with a felt plate 15 adapted to engage the leather on the respective drying plate and to press the drying plate with the leather thereon against a heating plate 14, which latter is supported by a support 16.

Operation It may be assumed that the apparatus according to the present invention occupies the position shown in FIGS. 1 and 2 in which drying frame 7 with drying plate 9 is in its loading station while frame 6 with drying plate 9a is in its drying station. If it is now intended that a wet leather piece is to be processed, the said leather piece is in wet condition placed upon the relatively cold drying plate 9 after the working table ll has been raised by the cylinder piston systems 10 so as to properly support plate 9. In a manner known per se the leather on plate 9 is smoothed out for instance by means of a slicker. Thereupon, motor M (FIG. 1) is actuated to move plate 9 into the drying station as shown in FIG. 3 while at the same time plate 9a, which may be assumed as not having been loaded previously, moves into the loading station for being loaded. When frame 9 has reached its proper drying position in the drying station II, motor M is stopped and the cylinder piston means 12, 12a are actuated to move cover 11 with felt 15 thereon downwardly so as to engage plate 9 on frame 7 and to press the latter downwardly against the thrust of springs 13a until drying plate 9 engages heating plate 14. Thereupon, exhaust or vacuum means are actuated to create a vacuum with the result that an intensive evaporation of the water in the leather takes place while the leather itself is cooled by the evaporation cold and thus will not be heated up to an undue high temperature.

While such exhaust and vacuum means or installation may be of any suitable type, it may be of the type shown in the central and lower portion of FIG. 3. Thus, it may comprise a vacuum pump 17 which communicates with a chamber 21 through a conduit 18, a condenser 19 and a conduit 20. As will be seen from FIG. 3, chamber 21 is located in cover 11 between a partition 22 and a permeable support 23 for the felt plate 15. The steam originating from the wet leather and withdrawn with the air from chamber 21 is condensed as water in the condenser 19. Through conduit 24 cooling water is supplied to condenser 19, and this water is again withdrawn through conduit 25. The lower portion of FIG. 3 furthermore shows a heat exchanger 26 one end of which through a conduit 27 communicates with a heating chamber 28 located between support 16 and heating plate 14. The other end of heat exchanger 26 communicatesthrough a conduit 29 with a pump 30 communicating with heating chamber 28 through a conduit 31. For purposes of heating up plate 14, hot water is continuously circulated by pump 30 in the direction of the arrow A. The heat which has been transferred by the heating medium to heating plate 14 is made up by the supply of heat in the heat exchanger 26 through which is passed a heating coil 32. I

After the drying operation has been completed, the cylinder piston means 12, 12a are actuated to lift cover '11 off the dried leather and to permit springs 13a to lift the drying plate 9 oil the heating plate 14. Theretlpon, motor M is actuated to move the dried leather out of the drying station to the unloading station I While plate 9a, which in the meantime was loaded in the loading station, is now moved into the drying sta tion where it will be subjected to a drying operation described above. When drying plate 9 with the just dried leather has reached the unloading station I, the dried leather is removed, the drying plate 9 is cooled by air from blower B and is then ready for reloading.

As will be evident from the above, the arrangement according to the present invention permits smoothing out of the wet leather on a cold plate, which plate with the smoothed-out leather will subsequently be heated quickly in the drying station with the simultaneous e stablishment of a vacuum. This vacuum brings about a quick intensive evaporation of the water in the leather while the latter is being cooled by the evaporation cold and thus cannot assume any high temperature which might affect the quality of the leather.

Due to the fact that the drying plate in contrast to heretofore known drying plates does not consist of a wire fabric but of a thin sheet metal plate, the smoothing out of the leather and the elimination of any folds therein can be accomplished to a much better extent and quicker than herebefore possible.

It is, of course, to be understood that the present invention is, by no means, limited to the specific method and arrangement set forth above, but also comprises any modifications within the scope of the appended claims.

It is also to be understood that the heating plate may be heated in any convenient manner, for instance electrically, by steam or the like. If desired, the heating plate may also be omitted entirely and be replaced by other conventional heating means.

What I claim is:

1. An apparatus for vacuum drying fiat material, especially leather, which includes: a first station comprising means for smoothing out a wet piece of fiat material and readying the same for vacuum drying, a second station comprising means for vacuum drying a piece of wet material readied for drying at said first station, rail means respectively extending at a first level and at a second level from said first station to said second station, and two carriage means respectively movably mounted on said rail means for receiving pieces of material to be processed and movable on said rail means from said first station to said second station and from said second station to said first station, said carriage means being interconnected so that one carriage means will be at said first station when the other carriage means is at said second station and vice versa, that section of said rail means which is at said second station being variable as to height.

2. An apparatus according to claim 1, in which each of said carriage means has deta-chably mounted thereon a relatively thin and large surface area sheet metal plate for supporting the fiat material to be processed.

3. An apparatus for vacuum drying flat material, especially leather, which includes: a first station comprising means for smoothing out a wet piece of flat material and readying the same for vacuum drying, said first station also comprising a working table adjustable as to height and designed as a grate, a second station comprising means for vacuum drying a piece of wet material readied for drying at said first station, rail means respectively extending at a first level and at a second level from said first station to said second station, and two carriage means respectively movably mounted on said rail means for receiving pieces of material to be processed and movable on said rail means from said first station to said second station and from said second station to said first station, said carriage means being interconnected so that one carriage means will be at said first station when the other carriage means is at said second station and vice versa, that section of said rail means which is at said second station being variable as to height.

4. An apparatus according to claim 3, which includes blower means for delivering cooling air through said working table, and also includes fluid operable means for selectively raising and lowering said working table.

5. An apparatus for vacuum drying flat material especially leather, which includes: a first station comprising means for smoothing out a wet piece of flat material and readying the same for vacuum drying, a second station comprising means for vacuum drying a piece of wet material readied for vacuum drying at said first station, said last mentioned means including a heating table and pressing means operable selectively to be moved toward and away from said heating table, rail means respectively extending at a first level and a second level from said first station to said second station, two carriage means respectively movably mounted on said rail means for receiving pieces table for vacuum drying the piece of material on said last mentioned carriage means.

6. A method of drying pieces of flat material, especially leather, according to which each piece of flat material is dried separately and individually in a container With vacuum producing means, which includes the steps of: outside said container and on a rigid support smoothing out a single piece only at a time of a first piece of fiat material while at the same time subjecting a second single piece of flat material previously smoothed out outside said container on a rigid support to fluid pressure and vacuum drying while resting said last mentioned piece on the same rigid support on which it was previously smoothed out, and subsequently after completed drying of said second piece of flat material withdrawing the same at a first level from said container on its respective support and removing the dried piece from said last mentioned support and cooling the latter while at the same time moving said first piece of fiat material at a second level different from said first level into said container on the support on which it was previously smoothed out and subjecting said first piece of flat material to fluid pressure and vacuum drying and at the same time placing another wet piece of flat material on the support that is now outside said container.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM J. WYE, Primary Examiner. 

1. AN APPARATUS FOR VACUUM DRYING FLAT MATERIAL, ESPECIALLY LEATHER, WHICH INCLUDES: A FIRST STATION COMPRISING MEANS FOR SMOOTHING OUT A WET PIECE OF FLAT MATERIAL AND READYING THE SAME FOR VACUUM DRYING, A SECOND STATION COMPRISING MEANS FOR VACUUM DRYING A PIECE OF WET MATERIAL READIED FOR DRYING AT SAID FIRST STATION, RAIL MEANS RESPECTIVELY EXTENDING AT A FIRST LEVEL AND AT A SECOND LEVEL FROM SAID FIRST STATION TO SAID SECOND STATION, AND TWO CARRIAGE MEANS RESPECTIVELY MOVABLY MOUNTED ON SAID RAIL MEANS FOR RECEIVING PIECES OF MATERIAL TO BE PROCESSED AND MOVABLE ON SAID RAIL MEANS FROM SAID FIRST STATION TO SAID SECOND STATION AND FROM SAID SECOND STATION TO SAID FIRST STATION, SAID CARRIAGE MEANS BEING INTERCONNECTED SO THAT ONE CARRIAGE MEANS WILL BE AT SAID FIRST STATION WHEN THE OTHER CARRIAGE MEANS IS AT SAID SECOND STATION AND VICE VERSA, THAT SECTION OF SAID RAIL MEANS WHICH IS AT SAID SECOND STATION BEING VARIABLE AS TO HEIGHT. 